Iran has rounded up at least 10 reformist leaders, a party member said today, after President Mahmoud Ahmadinejad's re-election in a deeply-disputed vote sparked riots across Tehran.

Iran has rounded up at least 10 reformist leaders, a party member said on Sunday, after President Mahmoud Ahmadinejad's re-election in a deeply-disputed vote sparked riots across Tehran.

Ahmadinejad appeared on television on Saturday to declare his landslide victory over moderate challenger Mir Hossein Mousavi was "fair" after thousands of angry opposition supporters took to the streets in protest at alleged vote-rigging.

Iranian security forces have arrested at least 10 leaders of two reformist groups who backed ex-premier Mousavi in Friday's vote, an official from one group told AFP.

"At least 10 members of the Islamic Iran Participation Front and the Islamic Revolution Mujahedeen Organisation were arrested yesterday," said Rajab Ali Mazroei, a member of the front.

Thousands of Mousavi supporters swept through Tehran on Saturday shouting "Down with the Dictator" after final results showed the hardline incumbent Ahmadinejad winning almost 63 per cent of the vote.

Baton-wielding riot police firing tear gas clashed with protestors who pelted security forces with stones and set rubbish bins and police vehicles ablaze in unrest not seen since student riots a decade ago.